Devices and methods for treatment of luminal tissue

ABSTRACT

Devices and methods are provided for treatment of tissue in a body lumen with an electrode deployment device. Embodiments typically include a device with a plurality of electrodes having a pre-selected electrode density arranged on the surface of a support. The support may comprise a non-distensible electrode backing that is spirally furled about an axis and coupled to an expansion member such as an inflatable elastic balloon. In some embodiments, the balloon is inflated to selectively expose a portion of the electrode surface while maintaining the electrode density.

CROSS-REFERENCE

This application is a divisional application of Ser. No. 10/754,444,filed Jan. 9, 2004, which is incorporated herein by reference in itsentirety, and to which application we claim priority under 35 USC § 121.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to medical devices and methods.More particularly, the invention is directed to devices and methods fortreating the esophagus and other interior tissue regions of the body.

The human body has a number of internal body lumens or cavities locatedwithin, many of which have an inner lining or layer. These inner liningscan be susceptible to disease. In some cases, surgical intervention canbe required to remove the inner lining in order to prevent the spread ofdisease to otherwise healthy tissue located nearby.

Those with persistent problems with or inappropriate relaxation of thelower esophageal sphincter can develop a condition known asgastroesophageal reflux disease, manifested by classic symptoms ofheartburn and regurgitation of gastric and intestinal content. Thecausative agent for such problems may vary. Patients with severe formsof gastroesophageal reflux disease, no matter what the cause, cansometimes develop secondary damage of the esophagus due to theinteraction of gastric or intestinal contents with esophageal cells notdesigned to experience such interaction.

The esophagus is composed of three main tissue layers; a superficialmucosal layer lined by squamous epithelial cells, a middle submucosallayer and a deeper muscle layer. When gastroesophageal reflux occurs,the superficial squamous epithelial cells are exposed to gastric acid,along with intestinal bile acids and enzymes. This exposure may betolerated, but in some cases can lead to damage and alteration of thesquamous cells, causing them to change into taller, specialized columnarepithelial cells. This metaplastic change of the mucosal epithelium fromsquamous cells to columnar cells is called Barrett's esophagus, namedafter the British surgeon who originally described the condition.

Barrett's esophagus has important clinical consequences, since theBarrett's columnar cells can, in some patients, become dysplastic andthen progress to a certain type of deadly cancer of the esophagus. Thepresence of Barrett's esophagus is the main risk factor for thedevelopment of adenocarcinoma of the esophagus.

Accordingly, attention has been focused on identifying and removing thisabnormal Barrett's columnar epithelium in order to mitigate more severeimplications for the patient. Examples of efforts to properly identifyBarrett's epithelium, or more generally Barrett's esophagus, haveincluded conventional visualization techniques known to practitioners inthe field. Although certain techniques have been developed tocharacterize and distinguish such epithelium cells, such as disclosed inU.S. Pat. Nos. 5,524,622 and 5,888,743, there has yet to be shown safeand efficacious means of accurately removing undesired growths of thisnature from portions of the esophagus to mitigate risk of malignanttransformation.

Devices and methods for treating abnormal body tissue by application ofvarious forms of energy to such tissue have been described, and includelaser treatment, microwave treatment, radio frequency ablation,ultrasonic ablation, photodynamic therapy using photo sensitizing drugs,argon plasma coagulation, cryotherapy, and x-ray. These methods anddevices have been deficient however, since they do not allow for precisecontrol of the depth of penetration of the energy means. This is aproblem since uncontrolled energy application can penetrate too deeplyinto the esophageal wall, beyond the mucosa and submucosal layers, intothe muscularis externa, potentially causing esophageal perforation,stricture or bleeding. In addition, most of these methods and devicestreat only a small portion of the abnormal epithelium at one time,making treatment of Barrett's time consuming, tedious, and costly.

For example, U.S. Pat. No. 6,112,123 describes a device and method forablating tissue in the esophagus. The device and method, however, do notadequately control the application of energy to effect ablation oftissue to a controlled depth.

In many therapeutic procedures performed on layered tissue structures,it may be desirable to treat or affect only superficial layer(s) oftissue, while preserving intact the function of deeper layers. In thetreatment of Barrett's esophagus, the consequences of treating toodeeply and affecting layers beneath the mucosa can be significant. Forexample, treating too deeply and affecting the muscularis can lead toperforation or the formation of strictures. In the treatment ofBarrett's esophagus, it may be desired to treat the innermost mucosallayer, while leaving the intermediate submucosa intact. In othersituations, it may be desired to treat both the mucosal and submucosalayers, while leaving the muscularis layer intact.

One device which solves this problem is disclosed in U.S. Pat. No.6,551,310 B1. The abovementioned patent discloses a device and method oftreating abnormal tissue utilizing an expandable balloon with an arrayof closely spaced electrodes to uniformly treat a desired region oftissue. With the electrodes closely spaced in an array and for the sameenergy delivery parameters, the depth of ablation is limited to adistance that is related to the size and spacing between the electrodes,facilitating a uniform and controlled ablation depth across thetreatment area. However, because the diameter of the esophagus and otherlumens vary from patient to patient, the spacing between the electrodes(electrode density) will also vary as the balloon expands to accommodatethe different sizes. Therefore, in order to keep the electrode densityand corresponding ablation depth at the desired constant, a number ofdifferent catheters having a range of balloon diameters must beavailable and chosen appropriately to fit the corresponding size of thelumen.

Therefore, it would be advantageous to have devices and methods forcomplete treatment of an inner layer of luminal tissue to a desireddepth while ensuring that the deeper layers are unharmed. In particular,it would be desirable to provide an electrode deployment device that canexpand to uniformly engage the surface of a lumen and maintain aconstant electrode density as the device is expanded. At least some ofthese objectives will be met by the present invention.

2. Description of the Background Art

U.S. Pat. Nos. 5,524,622; 5,888,743; 6,112,123; and 6,551,310 have beendescribed above. Other patents of interest include U.S. Pat. Nos.4,658,836; 4,674,481; 4,776,349; 4,949,147; 4,955,377; 4,979,948;5,006,119; 5,010,895; 5,045,056; 5,117,828; 5,151,100; 5,277,201;5,428,658; 5,443,470; 5,454,809; 5,456,682; 5,496,271; 5,505,730;5,514,130; 5,542,916; 5,549,661; 5,566,221; 5,562,720; 5,569,241;5,599,345; 5,621,780; 5,648,278; 5,713,942; 5,730,128; 5,748,699;5,769,846; 5,769,880; 5,836,874; 5,846,196; 5,861,036; 5,891,134;5,895,355; 5,964,755; 6,006,755; 6,033,397; 6,041,260; 6,053,913;6,071,277; 6,073,052; 6,086,558; 6,091,993; 6,092,528; 6,095,966;6,102,908; 6,123,703; 6,123,718; 6,138,046; 6,146,149; 6,238,392;6,254,598; 6,258,087; 6,273,886; 6,321,121; 6,355,031; 6,355,032;6,363,937; 6,383,181; 6,394,949; 6,402,744; 6,405,732; 6,415,016;6,423,058; 6,423,058; 6,425,877; 6,428,536; 6,440,128; 6,454,790;6,464,697; 6,448,658; 6,535,768; 6,572,639; 6,572,578; and 6,589,238.Patent publications of interest include U.S. 2001/0041887; U.S.2002/0013581; U.S. 2002/0143325 A1; U.S. 2002/0156470; U.S.2002/0183739; U.S. 2003/0045869 A1; U.S. 2003/0009165 A1.

BRIEF SUMMARY OF THE INVENTION

According to the present invention, an electrode deployment device fortreatment of tissue in a body lumen comprises a plurality of electrodeshaving a pre-selected electrode density arranged on the surface of adimensionally stable support. An expansion member, such as an inflatableballoon, selectively exposes a portion of the electrode surface while aremaining portion remains shielded. Thus, the support can be expanded toengage the needed area of electrodes against targeted luminal tissuewhile maintaining the electrode density.

Although the following description will focus on embodiments configuredfor treatment of the esophagus, other embodiments may be used to treatany other suitable lumen in the body. In particular, the electrodedeployment devices and methods of the present invention may be usedwhenever uniform delivery of energy is desired to treat a controlleddepth of tissue in a lumen or cavity of the body, especially where suchbody structures may vary in size. Therefore, the following descriptionis provided for exemplary purposes and should not be construed to limitthe scope of the invention.

In many embodiments, the support may be comprised of a flexible,non-distensible backing. For example, the backing may comprise of athin, rectangular sheet of a polymer material such as polyimide,polyester or other flexible thermoplastic or thermosetting polymer film,polymer covered materials, or other nonconductive materials. The backingmay also be comprised of an electrically insulating polymer, with anelectro-conductive material, such as copper, deposited onto a surface.For example, an electrode pattern can be etched into the material tocreate an array of electrodes. In some embodiments, the support isspirally furled about an axis of the expansion member. The electrodepattern may be aligned in axial or traverse direction across thebacking, formed in a linear or non-linear parallel array or series ofbipolar pairs, or other suitable pattern. Depending on the desiredtreatment effect, the electrodes may be arranged to control the depthand pattern of treatment. For treatment of esophageal tissue, theelectrodes typically have a width from 0.1 mm to 3 mm, preferably from0.1 mm to 0.3 mm, and are spaced apart by a distance in the range from0.1 mm to 3 mm, typically from 0.1 mm to 0.3 mm.

The expandable member may comprise any material or configuration. Insome embodiments, for example, the expansion member comprises aninflatable balloon that is tapered at both ends. A balloon-typeexpansion member may be elastic, or optionally comprise anon-distensible bladder having a shape and a size in its fully expandedform that will extend in an appropriate way to the tissue to becontacted. Additional embodiments may comprise a basket, plurality ofstruts, an expandable member with a furled and an unfurled state, one ormore springs, foam, backing material that expands to an enlargedconfiguration when unrestrained, and the like.

In many aspects of the invention, the support is furled around theballoon so that the electrode-exposed surface of the support unfurls asthe balloon is inflated. For example, the support may be coiled into aloop and placed around an expandable balloon, so that a first end of thesupport is furled around the balloon overlapping the second end of thesupport. Some embodiments further include one or more elastic membersthat are attached to the second end and another point on the support tokeep the backing constrained until being unfurled. As the balloonexpands, the elastic members allow the support to unfurl and furtherexpose additional electrodes that had previously been shielded by theoverlapping portion of the support.

In another embodiment, the support is attached at its first end to aballoon, and a second end is unattached and furled around the balloonoverlapping the first end of the support. As the balloon expands, thesupport unfurls and exposes additional electrodes that had previouslybeen shielded by the overlapping portion of the support. Alternatively,the support is attached at its midpoint to the surface of the balloonand the ends of the support are furled in opposite directions around theballoon

In one aspect of the invention, a first support is attached at itsmidpoint to an expandable balloon so that the ends of the first supportfurl around the balloon in opposite directions. A second support is alsoattached at its midpoint to the balloon opposite from the first support,the ends of the second support also being furled in opposite directionsaround the balloon and overlapping the ends of the first support. Someembodiments further include one or more elastic members coupled to thefirst and second supports. As the balloon expands, the elastic membersallow the supports to unfurl with respect to each other and furtherexpose additional electrodes of the first support that had previouslybeen shielded by the overlapping portion of the second support.

In some embodiments, the support is spirally furled inside a containerhaving a slot down its axis through which one end of the furled supportcan pass. The container may comprise of a tubular-shaped, semi-rigidmaterial, such as a plastic. A balloon surrounds a portion of theoutside surface of the container, avoiding the opening provided by theaxial slot. The support is partially unfurled from the container,through the slot and around the circumference of the balloon until itagain reaches the slot in the container where it is attached at one end.Alternatively, the support may be attached to the balloon at a locationproximal to the slot. When the balloon expands, the support unfurls fromthe container, exposing additional electrodes to compensate for theincreased surface area of the balloon, and maintaining the constantelectrode density on the surface of the support. Optionally, in someembodiments, the support is folded into a plurality of pleats inside thecontainer. In further embodiments, the support is attached to a shaftand is furled around the shaft inside the container. The shaft, forexample, may comprise an elongate, handheld rod of a flexible materialsuch as a metallic wire. Optionally, the device may further include atorsion spring coupled to the shaft.

In another aspect of the invention, the expansion member comprises aspiral spring. The spring, for example, may comprise of a wire, seriesof wires, or strip or sheet of spring temper or superelastic memorymaterial, such as 316 stainless steel or nitinol, that provides anunwinding force or constant stress or force while expanding from acompressed state. In some embodiments, the support is attached to theouter surface of the spring support. Optionally, the apparatus mayfurther comprise a shaft that is coupled to the spring.

In yet another aspect, the expansion member comprises a balloon havingan adhesive applied to selected areas of the balloon's outside surface,so that the balloon can be folded over at one or more of the adhesiveareas to form one or more creases. As the balloon expands, the creasesexpand to expose additional electrodes of the support that surrounds theballoon

In another embodiment of the invention, an electrode deploymentapparatus for treating tissue in a body lumen comprises: a shaft; asupport attached at one end to the distal end of the shaft and spirallyfurled about the shaft; a balloon slidably received on the shaft axiallyproximal to the support, wherein the balloon and support are retained ina sheath so that they may be advanced past the sheath once the apparatusis positioned at a treatment area, and wherein the balloon is furtheradvanced to the distal end of the shaft to expand the support.

In another aspect of the invention, an electrode deployment apparatuscomprising: a plurality of electrodes arranged on a surface of a supportat a pre-selected electrode density; an expansion member coupled toexpand the support to selectively expose a portion of the electrodesurface while shielding a remaining portion and maintaining theelectrode density; and a transesophageal catheter, wherein the expansionmember is disposed at a distal end of the catheter. The apparatus mayfurther comprise a RF power source coupled to the plurality ofelectrodes. In some embodiments, the apparatus may also include amultiplexer and/or temperature sensor coupled to the plurality ofelectrodes. Optionally, the apparatus might also have a control devicecoupled to the plurality of electrodes, the control device providingcontrolled positioning of the expandable member.

In still another aspect of the invention, an electrode deploymentapparatus for treatment of tissue in a human esophagus includes: aplurality of electrodes arranged on a surface of a support at apre-selected electrode density; and an expansion member coupled toexpand the support to engage the electrode surface to a wall of theesophagus while maintaining the electrode density. The electrodes may bearranged in a parallel pattern, and have a spacing between them of up to3 mm. The support may comprise a non-distensible electrode backing. Insome embodiments, the expandable member may comprise an inflatableballoon.

In many embodiments of the above electrode deployment apparatus, thesupport is furled at least partially around the balloon, so that thesupport unfurls as the balloon is inflated. The support may further beattached at one end to the surface of the balloon with the second end ofthe support being furled around the balloon. Alternatively, in someembodiments, the support is attached at its midpoint to the surface ofthe balloon, a first and second end of the support furled in oppositedirections around the balloon. Optionally, the support may be sized sothat the ends of the support do not overlap, thereby keeping the exposedarea of electrodes constant during expansion of the balloon.

In one aspect of the invention, a method for deploying electrodes totreat tissue in a body lumen comprises positioning an array ofelectrodes having a pre-selected electrode density within the bodylumen, and exposing an area of the array sufficient to engage a wall ofthe lumen while maintaining the electrode density, wherein the size ofthe exposed area may vary depending on the size of the body lumen. Inmany embodiments, positioning the array comprises transesophageallydelivering the array to a treatment area within the esophagus. Forexample, the array may be advanced via a catheter carrying the arraythrough the esophagus. Some embodiments further include applyingradiofrequency energy to tissue of the body lumen through theelectrodes. Optionally, such embodiments may also include applyingbipolar radiofrequency energy through a multiplicity of bipolarelectrode pairs in the array. The electrodes in the array may beparallel, and have a width in the range from 0.1 mm to 3 mm, and bespaced-apart by a distance in the range from 0.1 mm to 3 mm. Generally,the total radiofrequency energy delivered to the esophageal tissue willbe in the range from 1 joules/cm² to 50 joules/cm², usually being from 5joules/cm² to 50 joules/cm². In many embodiments, the array comprises anon-distensible, electrode support that is furled about an axis of theexpansion member, wherein expanding comprises unfurling the support toselectively expose a portion of the available electrode area. In mostcases, unfurling comprises expanding an expansion member such as aninflatable balloon within the furled support

In one aspect of the invention, the above method for deployingelectrodes to treat tissue in a body lumen further comprises: furlingthe support about an axis so that its ends overlap each other; couplingan elastic member to the support to retain the support from unfurlingfreely; placing the balloon within the circumference of the furledsupport; advancing the support assembly to a desired treatment region;and expanding the balloon to deploy the backing against a wall of thelumen.

In yet another embodiment of the invention, a method for deployingelectrodes to treat tissue in a body lumen comprises: furling a supportwith an array of electrodes having a pre-selected density about thedistal end of a shaft having a balloon slidably received on the shaftproximal to the support; positioning the balloon and support inside asheath; positioning the sheath assembly near a treatment area; advancingthe balloon and support past the sheath; advancing the balloon to thedistal end of the shaft; positioning the balloon and support at thetreatment area; and expanding the balloon to deploy the backing againstthe lumen.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view of portions of an upper digestive tract in ahuman.

FIG. 2 is a schematic view of a device of the invention, in a compressedmode, within an esophagus

FIG. 3 is a schematic view of a device of the invention, in an expandedmode, within an esophagus

FIG. 4 is a schematic view of another embodiment of a device of theinvention.

FIG. 5 shows a top view and a bottom view of an electrode pattern of thedevice of FIG. 4.

FIG. 6 shows the electrode patterns of the device of FIG. 3.

FIG. 7 shows the electrode patterns that may be used with a device ofthe invention.

FIG. 8 is an enlarged cross-sectional view of a device of the inventionin an expanded configuration.

FIG. 9 shows an enlarged cross-sectional view of the device of FIG. 8 ina more expanded configuration.

FIG. 10 is an enlarged cross-sectional view of a device of the inventionin an expanded configuration.

FIG. 11 is an enlarged cross-sectional view of the device of FIG. 10 ina compressed configuration.

FIG. 12 shows an enlarged cross-sectional view of another embodiment ofa device of the invention in an expanded configuration

FIG. 13 shows an enlarged cross-sectional view of yet another embodimentof a device of the invention in an expanded configuration.

FIG. 14A is a perspective cross-sectional view of another embodiment ofa device of the invention in a compressed configuration.

FIG. 14B is a perspective cross-sectional view of the device of FIG. 10in a compressed configuration.

FIG. 15 shows enlarged cross-sectional views of several embodiments of adevice of the invention in an expanded configuration.

FIG. 16 is an enlarged cross-sectional view of another embodiment of adevice of the invention in an expanded configuration.

FIG. 17 shows an enlarged cross-sectional view of another embodiment ofa device of the invention in an expanded configuration.

FIG. 18 is an enlarged cross-sectional view of yet another embodiment ofa device of the invention in a partially expanded configuration.

DETAILED DESCRIPTION OF THE INVENTION

In various embodiments, the present invention provides devices andmethods for treating, at a controlled and uniform depth, the innerlining of a lumen or cavity within a patient. It will be appreciatedthat the present invention is applicable to a variety of differenttissue sites and organs, including but not limited to the esophagus. Atreatment apparatus including an energy delivery device comprising anexpandable electrode array is provided. At least a portion of thedelivery device is positioned at the tissue site, where the electrodearray is expanded to contact the tissue surface. Sufficient energy isdelivered from the electrode array to impart a desired therapeuticeffect, such as ablation as described below, to a discreet layer oftissue.

Certain disorders can cause the retrograde flow of gastric or intestinalcontents from the stomach 12, into the esophagus 14, as shown by arrowsA and B in FIG. 1. Although the causation of these problems are varied,this retrograde flow may result in secondary disorders, such asBarrett's esophagus, which require treatment independent of and quitedifferent from treatments appropriate for the primary disorder—such asdisorders of the lower esophageal sphincter 16. Barrett's esophagus isan inflammatory disorder in which the stomach acids, bile acids andenzymes regurgitated from the stomach and duodenum enter into the loweresophagus causing damage to the esophageal mucosa. When this type ofretrograde flow occurs frequently enough, damage may occur to esophagealepithelial cells 18. In some cases the damage may lead to the alterationof the squamous cells, causing them to change into taller specializedcolumnar epithelial cells 20. This metaplastic change of the mucosalepithelium from squamous cells to columnar cells is called Barrett'sesophagus. Although some of the columnar cells may be benign, others mayresult in adenocarcinoma.

In one aspect, the present invention provides devices and methods fortreating columnar epithelium of selected sites of the esophagus in orderto mitigate more severe implications for the patient. In manytherapeutic procedures according to the present invention, the desiredtreatment effect is ablation of the tissue. The term “ablation” as usedherein means thermal damage to the tissue causing tissue or cellnecrosis. However, some therapeutic procedures may have a desiredtreatment effect that falls short of ablation, e.g. some level ofagitation or damage that is imparted to the tissue to inure a desiredchange in the cellular makeup of the tissue, rather than necrosis of thetissue. With the present invention, a variety of different energydelivery devices can be utilized to create a treatment effect in asuperficial layer of tissue, while preserving intact the function ofdeeper layers, as described hereafter.

Cell or tissue necrosis can be achieved with the use of energy, such asradiofrequency energy, at appropriate levels to accomplish ablation ofmucosal or submucosal level tissue, while substantially preservingmuscularis tissue. Such ablation is designed to remove the columnargrowths 20 from the portions of the esophagus 14 so affected.

As illustrated in FIGS. 2 and 3, a treatment apparatus 10 constructed inaccordance with the principles of the present invention, includes anelongated catheter sleeve 22, that is configured to be inserted into thebody in any of various ways selected by the medical provider. Apparatus10 may be placed, (i) endoscopically, e.g. through esophagus 14, (ii)surgically or (iii) by other means. As shown in FIG. 2, the apparatus isdelivered to the treatment area within the esophagus while in anon-expanded state. This low-profile configuration allows forease-of-access to the treatment site without discomfort or complicationsto the patient. Proper treatment of the tissue site, however, requiresthe apparatus to expand to the diameter of the esophagus, as illustratedin FIG. 3. Once expanded, the apparatus can uniformly deliver treatmentenergy to the desired tissue site.

When an endoscope (not shown) is used, catheter sleeve 22 can beinserted in the lumen of the endoscope, or catheter sleeve 22 can bepositioned along the outside of the endoscope. Alternately, an endoscopemay be used to visualize the pathway that catheter 22 should followduring placement. As well, catheter sleeve 22 can be inserted intoesophagus 14 after removal of the endoscope.

An electrode support 24 is provided and can be positioned at a distalend 26 of catheter sleeve 22 to provide appropriate energy for ablationas desired. Electrode support 24 has a plurality of electrode areasegments 32 attached to the surface of the support. The electrodes 32can be configured in an array 30 of various patterns to facilitate aspecific treatment by controlling the electrode size and spacing(electrode density). In various embodiments, electrode support 24 iscoupled to an energy source configured for powering array 30 at levelsappropriate to provide the selectable ablation of tissue to apredetermined depth of tissue.

In many embodiments, the support 24 may comprise a flexible,non-distensible backing. For example, the support 24 may comprise of athin, rectangular sheet of polymer materials such as polyimide,polyester or other flexible thermoplastic or thermosetting polymer film.The support 24 may also comprise polymer covered materials, or othernonconductive materials. Additionally, the backing may include anelectrically insulating polymer, with an electro-conductive material,such as copper, deposited onto a surface so that an electrode patterncan be etched into the material to create an array of electrodes

Electrode support 24 can be operated at a controlled distance from, orin direct contact with the wall of the tissue site. This can be achievedby coupling electrode support 24 to an expandable member 28, which has aconfiguration that is expandable in the shape to conform to thedimensions of the expanded (not collapsed) inner lumen of the tissuesite or structure, such as the human lower esophageal tract. Suitableexpandable members 28 include but are not limited to a balloon,compliant balloon, balloon with a tapered geometry, basket, plurality ofstruts, an expandable member with a furled and an unfurled state, one ormore springs, foam, bladder, backing material that expands to anexpanded configuration when unrestrained, and the like.

Expandable member 28 can also be utilized to place electrode support 24,as well as to anchor the position of electrode support 24. This can beachieved with expandable member 28 itself, or other devices that arecoupled to member 28 including but not limited to an additional balloon,a plurality of struts, a bladder, and the like.

In many embodiments, electrode support 24 is utilized to regulate andcontrol the amount of energy transferred to the tissue at a tissue sitesuch as the inner wall of a lumen. Expandable member 28 can be bonded toa portion of catheter sleeve 22 at a point spaced from distal end 26.Electrode support 24 may be furled at least partially around the outsidecircumference of expandable member 28 so that when expansion member 28expands, support 24 adapts to the changing circumference whilemaintaining a constant electrode density per unit area. Energy istransferred from the catheter sleeve 22 to the electrode support 24 onexpandable member 28. By way of illustration, one type of energydistribution that can be utilized is disclosed in U.S. Pat. No.5,713,942, incorporated herein by reference, in which an expandableballoon is connected to a power source, which provides radio frequencypower having the desired characteristics to selectively heat the targettissue to a desired temperature

In one embodiment, catheter sleeve 22 includes a cable that contains aplurality of electrical conductors surrounded by an electricalinsulation layer, with an electrode support 24 positioned at distal end26. A positioning and distending device can be coupled to cathetersleeve 22. The positioning and distending device can be configured andsized to contact and expand the walls of the body cavity in which it isplaced, by way of example and without limitation, the esophagus. Thepositioning and distending device can be at different positions ofelectrode support 24, including but not limited to its proximal and/ordistal ends, and also at its sides.

As shown in FIGS. 2 and 3, in an embodiment of the present invention,electrode support 24 can be positioned so that energy is uniformlyapplied to all or a portion of the inner circumference of the lumenwhere treatment is desired. This can be accomplished by firstpositioning apparatus 10 to the treatment area in a compressedconfiguration with the electrode support 24 furled around the outsidecircumference of expandable member 28. Once the apparatus is advanced tothe appropriate site, expandable member 28 is inflated, which unfurlselectrode support 24 to engage the internal wall of the lumen. In someembodiments, additional electrode support may unfurl from slot 34, shownin greater detail as slot 166 in FIGS. 10 through 12, where theelectrode support was previously shielded prior to expansion. Thedesired treatment energy may then be delivered to the tissue asnecessary. As illustrated in FIG. 3, the electrode support 24 uniformlyengages the inner wall of the lumen with an array of electrodes 30having a constant density so that the energy is uniformly applied to allor a portion of the circumference of the inner lumen of the esophagus orother tissue site

One way to ensure that the energy is uniformly applied to thecircumference of the inner lumen of the esophagus is the use of a vacuumor suction element to “pull” the esophageal wall, or other tissue site,against the outside circumference of expandable member 28. This suctionelement may be used alone to “pull” the esophageal wall into contactwith electrode support 24, carried on or by catheter sleeve 22 withoutthe use of expandable member 28, or in conjunction with expandablemember 28 to ensure that the wall is in contact with electrode support24 while carried on the outside of expandable member 28. This sameresult can be achieved with any of the electrode supports 24 utilized,and their respective forms of energy, with respect to expandable member28 so that the energy is uniformly applied.

Electrode support 24 can deliver a variety of different types of energyincluding but not limited to, radio frequency, microwave, ultrasonic,resistive heating, chemical, a heatable fluid, optical including withoutlimitation, ultraviolet, visible, infrared, collimated or noncollimated, coherent or incoherent, or other light energy, and the like.It will be appreciated that the energy, including but not limited tooptical, can be used in combination with one or more sensitizing agents.

The energy source may be manually controlled by the user and is adaptedto allow the user to select the appropriate treatment time and powersetting to obtain a controlled depth of ablation. The energy source canbe coupled to a controller (not shown), which may be a digital or analogcontroller for use with the energy source, including but not limited toan RF source, or a computer with software. When the computer controlleris used it can include a CPU coupled through a system bus. The systemmay include a keyboard, a disk drive, or other non-volatile memorysystem, a display and other peripherals known in the art. A programmemory and a data memory will also be coupled to the bus.

The depth of treatment obtained with apparatus 10 can be controlled bythe selection of appropriate treatment parameters by the user asdescribed in the examples set forth herein. One important parameter incontrolling the depth of treatment is the electrode density of the array30. As the spacing between electrodes decreases, the depth of treatmentof the affected tissue also decreases. Very close spacing of theelectrodes assures that the current and resulting ohmic heating islimited to a very shallow depth so that injury and heating of thesubmucosal layer are minimized. For treatment of esophageal tissue usingRF energy, it may be desirable to have a width of each RF electrode tobe no more than, (i) 3 mm, (ii) 2 mm, (iii) 1 mm (iv) 0.5 mm or (v) 0.3mm (vi) 0.1 mm and the like. Accordingly, it may be desirable to have aspacing between adjacent RF electrodes to be no more than, (i) 3 mm,(ii) 2 mm, (iii) 1 mm (iv) 0.5 mm or (v) 0.3 mm (vi) 0.1 mm and thelike. The plurality of electrodes can be arranged in segments, with atleast a portion of the segments being multiplexed. An RF electrodebetween adjacent segments can be shared by each of adjacent segmentswhen multiplexed.

The electrode patterns of the present invention may be varied dependingon the length of the site to be treated, the depth of the mucosa andsubmucosa, in the case of the esophagus, at the site of treatment andother factors. The electrode pattern 30 may be aligned in an axial ortraverse direction across the electrode support 24, or formed in alinear or non-linear parallel matrix or series of bipolar pairs ormonopolar electrode. One or more different patterns may be coupled tovarious locations of expandable member 28. For example, an electrodearray, as illustrated in FIGS. 6(a) through 6(c), may comprise a patternof bipolar axial interlaced finger electrodes 68, six bipolar rings 62with 2 mm separation, or monopolar rectangles 65 with 1 mm separation.Other suitable RF electrode patterns which may be used include, withoutlimitation, those patterns shown in FIGS. 7(a) through 7(d) as 46, 48,50 and 52, respectively. Pattern 46 is a pattern of bipolar axialinterlaced finger electrodes with 0.3 mm separation. Pattern 48 includesmonopolar bands with 0.3 mm separation. Pattern 52 includes bipolarrings with 0.3 mm separation. Pattern 50 is electrodes in a pattern ofundulating electrodes with 0.2548 mm separation.

A probe sensor may also be used with the system of the present inventionto monitor and determine the depth of ablation. In one embodiment, oneor more sensors (not shown), including but not limited to thermal andthe like, can be included and associated with each electrode segment 32in order to monitor the temperature from each segment and then controlthe energy delivery to that segment. The control can be by way of anopen or closed loop feedback system. In another embodiment, theelectroconductive member can be configured to permit transmission ofmicrowave energy to the tissue site. Treatment apparatus 10 can alsoinclude steerable and directional control devices, a probe sensor foraccurately sensing depth of ablation, and the like.

Referring to FIG. 4, one embodiment of the invention comprises anelectrode deployment device 100 having an electrode support 110 furledaround the outside of an inflatable balloon 116 that is mounted on acatheter sleeve 118. Support 110 has an electrode array 112 etched onits surface, and is aligned between edges 120 that intersect the taperregion located at the distal and proximal ends of balloon 116. Support110 is attached at a first end 122 to balloon 116 with an adhesive. Thesecond end 124 of the support is furled around the balloon, overlappingthe first end 122.

FIG. 5 shows a bottom view 150 and a top view 152 of the electrode array112 of support 110. In this embodiment, the array 112 has 20 parallelbars, 0.25 mm wide, separated by gaps of 0.3 mm. The bars on the circuitform twenty complete continuous rings around the circumference ofballoon 116. Electrode array 112 can be etched from a laminateconsisting of copper on both sides of a polyimide substrate. One end ofeach copper bar has a small plated through hole 128, which allowssignals to be passed to these bars from 1 of 2 copper junction blocks156 and 158, respectively, on the back of the laminate. One junctionblock 156 is connected to all of the even numbered bars, while the otherjunction block 158 is connected to all of the odd numbered bars.

As shown in FIGS. 4 and 5, each junction block 156 and 158 is then wiredto a bundle of AWG wires 134. The wiring is external to balloon 116,with the distal circuit wires affixed beneath the proximal circuit. Uponmeeting the catheter sleeve of the device, these bundles 134 can besoldered to three litz wire bundles 136. One bundle 136 serves as acommon conductor for both circuits while the other two bundles 136 arewired individually to each of the two circuits. The litz wires areencompassed with heat shrink tubing along the entire length of thecatheter sleeve 118 of the device. Upon emerging from the proximal endof the catheter sleeve, each of these bundles 136 is individuallyinsulated with heat shrink tubing before terminating to a mini connectorplug 138. Under this configuration, power can be delivered to either orboth of the two bundles so that treatment can be administered to aspecific area along the array.

They connector 142 at the proximal end of the catheter sleeve includesaccess ports for both the thru lumen 144 and the inflation lumen 146.The thru lumen spans the entire length of the balloon catheter and exitsat tip 148 at the distal end of balloon 116. The inflation lumen 146 iscoupled to balloon 116 so that the balloon can be inflated by deliveryof a liquid, such as water, a gas, such as air, or the like.

In some embodiments, for delivery of apparatus 100, support 110 istightly furled about deflated balloon 116 and placed with within asheath (not shown). During deployment, this sheath is retracted alongthe shaft to expose support 110. In alternative embodiments, an elasticmember (not shown) may be coupled to the support 110 to keep the supportfurled around balloon 116 during deployment of apparatus 100

Apparatus 100, illustrated in FIG. 4, is designed for use with the RFenergy methods as set forth herein. Electrode array 112 can be activatedwith approximately 300 watts of radio frequency power for the length oftime necessary to deliver from 1 J/cm² to 50 J/cm² To determine theappropriate level of energy, the diameter of the lumen is evaluated sothat the total treatment area can be calculated. A typical treatmentarea will require total energy ranging from 1 J/cm² to 50 J/cm².

In order to effectively ablate the mucosal lining of the esophagus andallow re-growth of a normal mucosal lining without creating damage tounderlying tissue structures, it is preferable to deliver theradiofrequency energy over a short time span in order to reduce theeffects of thermal conduction of energy to deeper tissue layers, therebycreating a “searing” effect. It is preferable to deliver theradiofrequency energy within a time span of less than 5 seconds. Anoptimal time for effective treatment is less than 1 second, andpreferably less than 0.5 second or 0.25 seconds. The lower bound on timemay be limited by the ability of the RF power source to deliver highpowers. Since the electrode area and consequently the tissue treatmentarea can be as much as several square centimeters, RF powers of severalhundred watts would be required in order to deliver the desired energydensity in short periods of time. This may pose a practical limitationon the lower limit of time. However, an RF power source configured todeliver a very short, high power, pulse of energy could be utilized.Using techniques similar to those used for flash lamp sources, or othertypes of capacitor discharge sources, a very high power, short pulse ofRF energy can be created. This would allow treatment times of a fewmilliseconds or less. While this type of approach is feasible, inpractice a more conventional RF source with a power capability ofseveral hundred watts may be preferred.

For an apparatus 100 employing a different length electrode array 112,or balloon 116 is expanded to a different diameter, the desired powerand energy settings can be scaled as needed to deliver the same powerand energy per unit area. These changes can be made either automaticallyor from user input to the RF power source. If different treatment depthsare desired, the geometry of electrode array 112 can be modified tocreate either a deeper or more superficial treatment region. Making theelectrodes of array 112 more narrow and spacing the electrodes closertogether reduces the treatment depth. Making the electrodes of array 112wider, and spacing the electrodes further apart, increases the depth ofthe treatment region. Non-uniform widths and spacings may be exploitedto achieve various treatment effects.

In order to ensure good contact between the esophageal wall andelectrode array 112, slight suction may be applied to the through lumentube to reduce the air pressure in the esophagus 14 distal to balloon116. The application of this slight suction can be simultaneouslyapplied to the portion of the esophagus 14 proximal to balloon 116. Thissuction causes the portion of the esophageal wall distended by balloon116 to be pulled against electrode arrays 112 located on balloon 116.

Various modifications to the above mentioned treatment parameters withelectrode array 112 can be made to optimize the treatment of theabnormal tissue. To obtain shallower lesions, the radiofrequency energyapplied may be increased while decreasing the treatment time. Thepatterns of electrode array 112 may be modified, such as shown in FIG.7, to improve the evenness and shallowness of the resulting lesions. Thedevices and methods of the present invention can also be modified toincorporate temperature feedback, resistance feedback and/ormultiplexing electrode channels.

Because the size of the lumen to be treated will vary from patient topatient, the device of the present invention is configured to variablyexpand to different diameters while maintaining a uniform and constantdensity of electrodes in contact with the tissue surface. In oneembodiment of the present invention shown in FIGS. 10 and 11, anelectrode array is arranged on a support 160 comprising a flexibleelectrode backing that is axially furled inside a cylindrical container162. Support 160 may comprise a non-distensible, rectangular-shaped thinsheet formed from a polymer material, such as polyimide. An expandablemember 164, such as an elastic balloon, surrounds a portion of theoutside surface of container 162, leaving access to an opening that isformed from an axial slot 166 down the center of container 162. One endof support 160 is partially unfurled through slot 166 of container 162,and around the circumference of the expandable member 164 until it againreaches slot 166 where it is attached to either expandable member 164 orcontainer 162

FIG. 11 illustrates the apparatus 200 of the present invention in itscompressed configuration. To engage the inner surface of a lumen that islarger than the compressed diameter of the catheter, expandable member164 is incrementally deployed until the desired pressure is exerted onthe inside wall of the lumen. In the method of this invention, it isdesirable to deploy the expandable member 164 sufficiently to occludethe vasculature of the submucosa, including the arterial, capillary orvenular vessels. The pressure to be exerted to do so should therefore begreater than the pressure exerted by such vessels, typically from 1 psigto 20 psig, usually from 5 psig to 10 psig. When the expandable member164 is inflated, support 160 unfurls from the container 162, exposingadditional electrodes to compensate for the increased surface area.Although the surface area of the electrode array increases, electrodedensity on the surface of support 160 remains constant. Energy,including but not limited to an RF signal, may then be delivered to theelectrodes to facilitate a uniform treatment to a precise depth oftissue. After the treatment has been administered, the expandable member164 is collapsed so that the apparatus 200 may be removed from thelumen, or reapplied elsewhere.

Suitable expandable members 164 include but are not limited to aballoon, balloon with a tapered geometry, basket, plurality of struts,an expandable member with a furled and an unfurled state, one or moresprings, foam, bladder, backing material that expands to an enlargedconfiguration when unrestrained, and the like. A balloon-type expansionmember 164 may be elastic, or a non-distensible bladder having a shapeand a size in its fully expanded form, which will extend in anappropriate way to the tissue to be contacted. In one embodiment shownin FIG. 12, container 162 may be centered within expansion member 164,such that expansion member 164 forms a “c” shape around container 162

In another embodiment, electrode support 160 can be formed from anelectrically insulating polymer, with an electroconductive material,such as copper, deposited onto a surface. An electrode pattern can thenbe etched into the material, and then the support can be attached to orfurled around an outer surface of a balloon. Bay way of example andwithout limitation, the electrode pattern may be aligned in an axial ortraverse direction across the support, formed in a linear or non-linearparallel matrix or series of bipolar pairs, or other suitable pattern asillustrated in FIGS. 5, 6 and 7.

In yet another embodiment illustrated in FIG. 12, electrode support 160is attached to a shaft 180, upon which support 160 is spirally coiledinside container 162. Shaft 180 rotates freely as the support isuncoiled from the expansion of balloon 164. After treatment has beenadministered, shaft 180 can be rotated in the opposite direction torecoil support 160 into the container, thereby facilitating removal ofapparatus 162 from the lumen. Shaft 180 may also be coupled with atorsion spring (not shown) so that a retraction and/or constanttorsional force is applied to the support 160 to keep the support snugagainst balloon 164 as it expands or compresses.

FIG. 13 illustrates another embodiment of the present inventionutilizing a pleated electrode support. The electrode support 178 ofapparatus 300 is repeatedly folded upon itself in an accordion-likepattern and attached at a first end 182 to the inside wall of container162. The support 178 passes through slot 166 of the container and aroundballoon 164 to the inside wall of slot 166 where it is attached at itssecond end. When balloon 164 is expanded, the pleats of support 178unfold, deploying the previously shielded electrodes to accommodate theincrease in surface area of the balloon.

FIGS. 14A and 14B show an electrode deployment device 400 whereinelectrode support 160 is attached to and spirally furled about thedistal end of shaft 180. An expandable balloon 164 is positioned onshaft 180 proximal to support 160, and is mounted on shaft 180 so thatit can freely slide axially along the shaft. Support 160 is retained ina compressed state by sheath 184, which shields both the support andballoon 164 from the interior walls of the lumen while the device 400 isadvanced to the treatment region. When the device 400 is at theappropriate location, the catheter assembly 186 is advanced out of thesheath 184, causing the electrode support 160 to slightly expand. Theballoon 164 is then advanced to the distal end of the shaft 180 so thatit is surrounded by the inside circumference of the support 160. Balloon164 is then expanded to match the inside diameter of the treatmentregion, further exposing additional electrodes on the support as itunfurls to accommodate the increase in surface area of the balloon.

FIGS. 15A-C illustrate additional embodiments of the electrode support160 of the present invention. In FIG. 15A, support 160 is attached at afirst end 168 to a expandable balloon 164. The second end 170 of thesupport 160 is furled around the balloon, overlapping the first end 168.In FIG. 15B, support 160 is attached at its midpoint 172 to expandableballoon 164, the ends of the support furling around the balloon inopposite directions such that the first end 168 is overlapped by thesecond end 170. As the balloon 164 expands, the support 160 unfurls andfurther exposes additional electrodes that had previously been shieldedby the overlapping portion of the support

FIG. 15C illustrates another embodiment of the present inventionutilizing two separate electrode array supports. A first support 160 isattached at its midpoint 172 to an expandable balloon 164, the ends ofthe first support furling around the balloon in opposite directions. Asecond support 174 is also attached at its midpoint 176 to the balloon164 opposite from the first support 160, the ends of the second support174 also being furled in opposite directions around the balloon andoverlapping the ends of the first support 160. One or more elasticmembers (not shown) are attached to the ends of the second support andanother point on the first support. As the balloon is expanded, theelastic members allow the supports to unfurl with respect to each otherand further expose additional electrodes of the first support that hadpreviously been shielded by the overlapping portion of the secondsupport.

FIG. 8 illustrates another embodiment where the support 160 is furledaround balloon 164 in a non-overlapping configuration. In the depictedembodiment, support 160 is attached at one end 168 to the balloon 164and the second end 170 is furled around the circumference of the balloonuntil it reaches the first attached end, where it terminates. Whenballoon 164 expands, the ends of the support expand with it, forming agap 188 between each end that increases with the increasingcircumference of the balloon. One advantage of this configuration isthat the electrode surface area remains constant when the balloon isexpanding. However, a portion of the circumference will be void of atreatment surface due to the gap in the electrode support. Inalternative embodiments shown in FIG. 9, the non-overlapping support 160may also comprise one or more supports that are attached at theirmidpoint 172, such that ends 168 and 170 form gap 188 when the balloon164 is expanded.

In various embodiments, one or more elastic members are attached to thesupport to prevent the support from prematurely unfurling. Asillustrated in FIG. 17, elastic member 190 is attached to one end ofelectrode support 160 and to another point on the support free ofelectrodes. The elastic member 190 keeps the furled support 160 at abasic diameter smaller than that of the lumen to be treated. Anexpandable balloon 164 is then inserted within the inner diameter ofsupport 160, and the assembly 600 is advanced to the treatment sitewhere balloon 164 is expanded to engage the inner surface of the lumen.As balloon 164 is expanded, the elastic member 190 allows the support tounfurl and further expose additional electrodes while also keeping thefree end of support 160 from shifting out of alignment with theremainder of the array. After treatment has been administered, elasticmember 190 recompresses support 160 while balloon 164 deflates,returning support 160 to a reduced diameter to facilitate removal of theassembly 600 from the lumen.

FIG. 16 shows an electrode deployment device 500 wherein electrodesupport 160 is attached to a spiral spring 188. Spring 188 may include,but is not limited to a wire, series of wires, or strip or sheet of aspring temper or superelastic material that provides a retraction and/ora constant stress or force while compressed, such as a 316 stainlesssteel or nitinol. It should be noted however, that any material suitableas a retraction and/or a constant force spring may be used. Spring 188is attached at one end to a shaft 180. To facilitate treatment, thespring 188 and support are coiled about shaft 180 and placed inside asheath (not shown). Device 500 is then advanced to the treatment region,and the sheath is retracted, causing the spring 188 to expand and matewith the wall of the lumen.

FIG. 18 illustrates another embodiment of the present inventionutilizing an adhesive to compress a pre-selected electrode array.Apparatus 700 includes a flexible electrode support 160 that is foldedinto a loop and attached at its ends. The edges of a portion of support160 are coated with an adhesive 192 in a region where the adhesive willnot cover the conductive elements of the electrode. The support 160 iscreased upon itself at the adhesive regions to form one or more folds194 of unexposed electrodes. The adhesive 192 that is applied willpreferably not form a strong bond, but rather have a low adhesivequality so that a reasonable amount of deployment force will allow thebond to pull apart and deploy and expose only the amount of electrodearea required to have complete circumferential contact with the lumen.An expansion balloon 164 is positioned within the looped support 160.The apparatus 700 is then advanced to a treatment region, and theballoon 164 is inflated. As balloon 164 expands, the pressure on thesupport increases, forcing the folds 194 to separate and incrementallyexpose additional electrodes on the support. The diameter of theapparatus 700 increases until the proper engagement with the lumen wallis achieved.

The foregoing description of a preferred embodiment of the invention hasbeen presented for purposes of illustration and description. It is notintended to be exhaustive or to limit the invention to the precise formsdisclosed. Obviously, many modifications and variations will be apparentto practitioners skilled in this art. It is intended that the scope ofthe invention be defined by the following claims and their equivalents.

1. A method for treating tissue in an esophagus, the method comprising:inserting an electrode deployment apparatus into an esophagus, theelectrode deployment apparatus comprising an array of electrodesarranged on an exterior surface of an expandable support in apre-selected radial spacing at a first expansion size; radiallyexpanding the expandable support to a second expansion size to engageelectrodes with a wall of the esophagus while maintaining the radialspacing of the engaged electrodes about the exterior surface of thesupport; and delivering energy from the electrodes to the esophagus. 2.The method of claim 1, wherein the expandable support is dimensionallystable.
 3. The method of claim 1, wherein the electrode deploymentapparatus further comprises an expansion member coupled to theexpandable support.
 4. The method of claim 3, wherein the expandablesupport is furled about an axis and wherein expanding the supportradially comprises unfurling the support to selectively expose a portionof the array.
 5. The method of claim 4, wherein unfurling comprisesexpanding the expansion member.
 6. The method of claim 5, whereinexpanding the expansion member comprises inflating a balloon.
 7. Themethod of claim 6, wherein expanding the expansion member comprisesunfurling the support by applying force against a retaining elasticmember adapted to retain the support from unfurling freely.
 8. Themethod of claim 7, further comprising removing the force against theelastic member after delivering energy to the esophagus.
 9. The methodof claim 3, wherein the electrode deployment apparatus further comprisesa movable shield associated with the expansion member, the expandingstep comprising exposing at least a first portion of the array andshielding a second portion of the array.
 13. The method of claim 1,wherein the energy is radiofrequency energy applied through amultiplicity of bipolar electrode pairs in the array.
 14. The method ofclaim 13, wherein the electrodes are parallel, have a width in the rangefrom 0.1 mm to 3 mm, and are spaced-apart by a distance in the rangefrom 0.1 mm to 3 mm.
 15. The method of claim 14, wherein theradiofrequency energy is delivered at a total dosage in the range from 1joules/cm² to 50 joules/cm².
 16. The method of claim 15, wherein theradiofrequency energy is delivered over a time period below 5 seconds.